The present invention relates to improvements in or relating to cigarette filters applying devices of the type in which cigarettes and filters are interconnected by adhesive junction bands.
It is already known to apply the filters to cigarettes by disposing the cigarettes in a two by two axial arrangement with a filter having a length twice of that required for a single cigarette therebetween disposed and by wrapping up a band of adhesive paper material to cover the full length of the filter section plus about 1/8" of the end section of the two cigarettes coaxial with said filter section.
The complex formed by one cigarette, by the filter section and by the other cigarette in axial relationship is thereinafter called "unit".
The steps above mentioned are usually carried out, for example, as described in the Italian Pat. No. 898,079 in the name of Hauni Werke Korker and Co. KG (priority of the German application No. 1911102.5 of Mar. 5, 1969), on the surface of a conveyor drum, to which said units and adhesive bands are supplied. The elements making each unit are interconnected by a rolling operation on an adhesive band.
Such a rolling operation is carried out within a rolling passage defined at one side by said drum and at the other side by a web moving at a different speed than that of the drum. Such a web, usually made of rubber or steel foil, is kept substantially equispaced relative to the surface of said drum by the units in said passage. During the rolling operation the units are subjected to compression by the web, which compression promotes the correct and tight wrapping of the bands.
The devices of the above described type have some drawbacks which comprise the regular operation thereof, particularly under certain conditions.
It has been found, for example, that said web exerts on the units a compressive action which is unsteady during the course of the entire rolling operation. This results in uneveness in the adherence of the wrapped up bands to the units. Serious drawbacks also arise in case where one or more consecutive units are absent at the rolling zone. In such a case, where units are frequently absent due to the rejection of units found as defective or incomplete upstream of the rolling zone, there is a shifting of a portion of the web from the condition of substantial concentric disposition with the conveyor drum, which results in a larger compression exerted on the units within said passage.
Particularly detrimental consequences occur in the case in which, due to the absence of a plurality of consecutive units, the web would come in contact with said conveyor drum.